They are not planes. They are stars but sky is not completely clear of clouds at some moments. If you watch his videos you will see that some of the stars disappear for the moment. It is better visible on moon picture and video.

i took a similar pic with my compact (it can only go 8 secs max) and upon loading them onto the computer, i saw a dotted line...there were 8 dots...and since the camera has a 8 sec max shutter speed, it explains why there were 8 dots (meaning the plane was flashing its lights every 1 sec)